/*
 * Copyright 2012 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */


#include "GrShaderCaps.h"

#include "GrContextOptions.h"
#include "SkJSONWriter.h"

////////////////////////////////////////////////////////////////////////////////////////////

static const char* shader_type_to_string(GrShaderType type) {
    switch (type) {
    case kVertex_GrShaderType:
        return "vertex";
    case kGeometry_GrShaderType:
        return "geometry";
    case kFragment_GrShaderType:
        return "fragment";
    }
    return "";
}

static const char* precision_to_string(GrSLPrecision p) {
    switch (p) {
    case kLow_GrSLPrecision:
        return "low";
    case kMedium_GrSLPrecision:
        return "medium";
    case kHigh_GrSLPrecision:
        return "high";
    default:
        SK_ABORT("Unexpected precision type.");
        return "";
    }
}

GrShaderCaps::GrShaderCaps(const GrContextOptions& options) {
    fGLSLGeneration = k330_GrGLSLGeneration;
    fShaderDerivativeSupport = false;
    fGeometryShaderSupport = false;
    fGSInvocationsSupport = false;
    fPathRenderingSupport = false;
    fDstReadInShaderSupport = false;
    fDualSourceBlendingSupport = false;
    fIntegerSupport = false;
    fTexelBufferSupport = false;
    fImageLoadStoreSupport = false;
    fShaderPrecisionVaries = false;
    fDropsTileOnZeroDivide = false;
    fFBFetchSupport = false;
    fFBFetchNeedsCustomOutput = false;
    fBindlessTextureSupport = false;
    fUsesPrecisionModifiers = false;
    fCanUseAnyFunctionInShader = true;
    fCanUseMinAndAbsTogether = true;
    fCanUseFractForNegativeValues = true;
    fMustForceNegatedAtanParamToFloat = false;
    fAtan2ImplementedAsAtanYOverX = false;
    fRequiresLocalOutputColorForFBFetch = false;
    fMustObfuscateUniformColor = false;
    fMustGuardDivisionEvenAfterExplicitZeroCheck = false;
    fFlatInterpolationSupport = false;
    fPreferFlatInterpolation = false;
    fNoPerspectiveInterpolationSupport = false;
    fMultisampleInterpolationSupport = false;
    fSampleVariablesSupport = false;
    fSampleMaskOverrideCoverageSupport = false;
    fExternalTextureSupport = false;
    fTexelFetchSupport = false;
    fVertexIDSupport = false;

    fVersionDeclString = nullptr;
    fShaderDerivativeExtensionString = nullptr;
    fGSInvocationsExtensionString = nullptr;
    fFragCoordConventionsExtensionString = nullptr;
    fSecondaryOutputExtensionString = nullptr;
    fExternalTextureExtensionString = nullptr;
    fTexelBufferExtensionString = nullptr;
    fNoPerspectiveInterpolationExtensionString = nullptr;
    fMultisampleInterpolationExtensionString = nullptr;
    fSampleVariablesExtensionString = nullptr;
    fFBFetchColorName = nullptr;
    fFBFetchExtensionString = nullptr;
    fImageLoadStoreExtensionString = nullptr;
    fMaxVertexSamplers = 0;
    fMaxGeometrySamplers = 0;
    fMaxFragmentSamplers = 0;
    fMaxCombinedSamplers = 0;
    fAdvBlendEqInteraction = kNotSupported_AdvBlendEqInteraction;

#if GR_TEST_UTILS
    fDisableImageMultitexturing = options.fDisableImageMultitexturing;
#else
    fDisableImageMultitexturing = false;
#endif
}

void GrShaderCaps::dumpJSON(SkJSONWriter* writer) const {
    writer->beginObject();

    writer->appendBool("Shader Derivative Support", fShaderDerivativeSupport);
    writer->appendBool("Geometry Shader Support", fGeometryShaderSupport);
    writer->appendBool("Geometry Shader Invocations Support", fGSInvocationsSupport);
    writer->appendBool("Path Rendering Support", fPathRenderingSupport);
    writer->appendBool("Dst Read In Shader Support", fDstReadInShaderSupport);
    writer->appendBool("Dual Source Blending Support", fDualSourceBlendingSupport);
    writer->appendBool("Integer Support", fIntegerSupport);
    writer->appendBool("Texel Buffer Support", fTexelBufferSupport);
    writer->appendBool("Image Load Store Support", fImageLoadStoreSupport);

    writer->appendBool("Variable Precision", fShaderPrecisionVaries);

    for (int s = 0; s < kGrShaderTypeCount; ++s) {
        GrShaderType shaderType = static_cast<GrShaderType>(s);
        writer->beginArray(SkStringPrintf("%s precisions",
                                          shader_type_to_string(shaderType)).c_str());
        for (int p = 0; p < kGrSLPrecisionCount; ++p) {
            if (fFloatPrecisions[s][p].supported()) {
                GrSLPrecision precision = static_cast<GrSLPrecision>(p);
                writer->beginObject(nullptr, false);
                writer->appendString("precision", precision_to_string(precision));
                writer->appendS32("log_low", fFloatPrecisions[s][p].fLogRangeLow);
                writer->appendS32("log_high", fFloatPrecisions[s][p].fLogRangeHigh);
                writer->appendS32("bits", fFloatPrecisions[s][p].fBits);
                writer->endObject();
            }
        }
        writer->endArray();
    }

    static const char* kAdvBlendEqInteractionStr[] = {
        "Not Supported",
        "Automatic",
        "General Enable",
        "Specific Enables",
    };
    GR_STATIC_ASSERT(0 == kNotSupported_AdvBlendEqInteraction);
    GR_STATIC_ASSERT(1 == kAutomatic_AdvBlendEqInteraction);
    GR_STATIC_ASSERT(2 == kGeneralEnable_AdvBlendEqInteraction);
    GR_STATIC_ASSERT(3 == kSpecificEnables_AdvBlendEqInteraction);
    GR_STATIC_ASSERT(SK_ARRAY_COUNT(kAdvBlendEqInteractionStr) == kLast_AdvBlendEqInteraction + 1);

    writer->appendBool("FB Fetch Support", fFBFetchSupport);
    writer->appendBool("Drops tile on zero divide", fDropsTileOnZeroDivide);
    writer->appendBool("Bindless texture support", fBindlessTextureSupport);
    writer->appendBool("Uses precision modifiers", fUsesPrecisionModifiers);
    writer->appendBool("Can use any() function", fCanUseAnyFunctionInShader);
    writer->appendBool("Can use min() and abs() together", fCanUseMinAndAbsTogether);
    writer->appendBool("Can use fract() for negative values", fCanUseFractForNegativeValues);
    writer->appendBool("Must force negated atan param to float", fMustForceNegatedAtanParamToFloat);
    writer->appendBool("Must use local out color for FBFetch", fRequiresLocalOutputColorForFBFetch);
    writer->appendBool("Must obfuscate uniform color", fMustObfuscateUniformColor);
    writer->appendBool("Must guard division even after explicit zero check",
                       fMustGuardDivisionEvenAfterExplicitZeroCheck);
    writer->appendBool("Flat interpolation support", fFlatInterpolationSupport);
    writer->appendBool("Prefer flat interpolation", fPreferFlatInterpolation);
    writer->appendBool("No perspective interpolation support", fNoPerspectiveInterpolationSupport);
    writer->appendBool("Multisample interpolation support", fMultisampleInterpolationSupport);
    writer->appendBool("Sample variables support", fSampleVariablesSupport);
    writer->appendBool("Sample mask override coverage support", fSampleMaskOverrideCoverageSupport);
    writer->appendBool("External texture support", fExternalTextureSupport);
    writer->appendBool("texelFetch support", fTexelFetchSupport);
    writer->appendBool("sk_VertexID support", fVertexIDSupport);

    writer->appendS32("Max VS Samplers", fMaxVertexSamplers);
    writer->appendS32("Max GS Samplers", fMaxGeometrySamplers);
    writer->appendS32("Max FS Samplers", fMaxFragmentSamplers);
    writer->appendS32("Max Combined Samplers", fMaxFragmentSamplers);
    writer->appendString("Advanced blend equation interaction",
                         kAdvBlendEqInteractionStr[fAdvBlendEqInteraction]);
    writer->appendBool("Disable image multitexturing", fDisableImageMultitexturing);

    writer->endObject();
}

void GrShaderCaps::initSamplerPrecisionTable() {
    // Determine the largest precision qualifiers that are effectively the same as lowp/mediump.
    //   e.g. if lowp == mediump, then use mediump instead of lowp.
    GrSLPrecision effectiveMediumP[kGrShaderTypeCount];
    GrSLPrecision effectiveLowP[kGrShaderTypeCount];
    for (int s = 0; s < kGrShaderTypeCount; ++s) {
        const PrecisionInfo* info = fFloatPrecisions[s];
        effectiveMediumP[s] = info[kHigh_GrSLPrecision] == info[kMedium_GrSLPrecision] ?
                                  kHigh_GrSLPrecision : kMedium_GrSLPrecision;
        effectiveLowP[s] = info[kMedium_GrSLPrecision] == info[kLow_GrSLPrecision] ?
                               effectiveMediumP[s] : kLow_GrSLPrecision;
    }

    // Determine which precision qualifiers should be used with samplers.
    for (int visibility = 0; visibility < (1 << kGrShaderTypeCount); ++visibility) {
        GrSLPrecision mediump = kHigh_GrSLPrecision;
        GrSLPrecision lowp = kHigh_GrSLPrecision;
        for (int s = 0; s < kGrShaderTypeCount; ++s) {
            if (visibility & (1 << s)) {
                mediump = SkTMin(mediump, effectiveMediumP[s]);
                lowp = SkTMin(lowp, effectiveLowP[s]);
            }

            GR_STATIC_ASSERT(0 == kLow_GrSLPrecision);
            GR_STATIC_ASSERT(1 == kMedium_GrSLPrecision);
            GR_STATIC_ASSERT(2 == kHigh_GrSLPrecision);

            GR_STATIC_ASSERT((1 << kVertex_GrShaderType) == kVertex_GrShaderFlag);
            GR_STATIC_ASSERT((1 << kGeometry_GrShaderType) == kGeometry_GrShaderFlag);
            GR_STATIC_ASSERT((1 << kFragment_GrShaderType) == kFragment_GrShaderFlag);
            GR_STATIC_ASSERT(3 == kGrShaderTypeCount);
        }

        uint8_t* table = fSamplerPrecisions[visibility];
        table[kUnknown_GrPixelConfig]             = lowp;
        table[kAlpha_8_GrPixelConfig]             = lowp;
        table[kAlpha_8_as_Alpha_GrPixelConfig]    = lowp;
        table[kAlpha_8_as_Red_GrPixelConfig]      = lowp;
        table[kGray_8_GrPixelConfig]              = lowp;
        table[kRGB_565_GrPixelConfig]             = lowp;
        table[kRGBA_4444_GrPixelConfig]           = lowp;
        table[kRGBA_8888_GrPixelConfig]           = lowp;
        table[kBGRA_8888_GrPixelConfig]           = lowp;
        table[kSRGBA_8888_GrPixelConfig]          = lowp;
        table[kSBGRA_8888_GrPixelConfig]          = lowp;
        table[kRGBA_8888_sint_GrPixelConfig]      = lowp;
        table[kRGBA_float_GrPixelConfig]          = kHigh_GrSLPrecision;
        table[kRG_float_GrPixelConfig]            = kHigh_GrSLPrecision;
        table[kAlpha_half_GrPixelConfig]          = mediump;
        table[kAlpha_half_as_Alpha_GrPixelConfig] = mediump;
        table[kAlpha_half_as_Red_GrPixelConfig]   = mediump;
        table[kRGBA_half_GrPixelConfig]           = mediump;
    }
}

void GrShaderCaps::applyOptionsOverrides(const GrContextOptions& options) {
#if GR_TEST_UTILS
    fDualSourceBlendingSupport = fDualSourceBlendingSupport && !options.fSuppressDualSourceBlending;
#endif
}